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 A373575 Numbers k such that k and k-1 both have at least two distinct prime factors. First element of the n-th maximal antirun of non-prime-powers. 14
 1, 15, 21, 22, 34, 35, 36, 39, 40, 45, 46, 51, 52, 55, 56, 57, 58, 63, 66, 69, 70, 75, 76, 77, 78, 85, 86, 87, 88, 91, 92, 93, 94, 95, 96, 99, 100, 105, 106, 111, 112, 115, 116, 117, 118, 119, 120, 123, 124, 130, 133, 134, 135, 136, 141, 142, 143, 144, 145 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The last element of the same antirun is given by A255346. An antirun of a sequence (in this case A361102) is an interval of positions at which consecutive terms differ by more than one. LINKS Table of n, a(n) for n=1..59. EXAMPLE The maximal antiruns of non-prime-powers begin: 1 6 10 12 14 15 18 20 21 22 24 26 28 30 33 34 35 36 38 39 40 42 44 45 46 48 50 MATHEMATICA Select[Range[100], !PrimePowerQ[#]&&!PrimePowerQ[#-1]&] CROSSREFS Runs of prime-powers: - length A174965 - min A373673 - max A373674 - sum A373675 Runs of non-prime-powers: - length A110969 - min A373676 - max A373677 - sum A373678 Antiruns of prime-powers: - length A373671 - min A120430 - max A006549 - sum A373576 Antiruns of non-prime-powers: - length A373672 - min A373575 (this sequence) - max A255346 - sum A373679 A000961 lists all powers of primes. A246655 lists just prime-powers. A057820 gives first differences of consecutive prime-powers, gaps A093555. A356068 counts non-prime-powers up to n. A361102 lists all non-prime-powers (A024619 if not including 1). Various run-lengths: A053797, A120992, A175632, A176246. Various antirun-lengths: A027833, A373127, A373403, A373409. Cf. A001359, A008864, A014963, A067774, A251092, A373669, A373670. Sequence in context: A033708 A343821 A294171 * A306102 A177024 A325037 Adjacent sequences: A373572 A373573 A373574 * A373576 A373577 A373578 KEYWORD nonn AUTHOR Gus Wiseman, Jun 18 2024 STATUS approved

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Last modified September 9 12:02 EDT 2024. Contains 375764 sequences. (Running on oeis4.)